[X4U] Numeric keys in keypad

[Paul Moortgat]

A friend with a new iMac has had a working keyboard till yesterday.   
Today the numeric keys from the numeric keypad will no longer work  
under 10.5.6.  But they work when he start Windows.
He also hooked a PC keyboard on his iMac but these numeric keys also  
don't work.  And the strange thing is that all the other keys (-+/*)  
work.  Just only the numbers will not work.  He can use the numbers on  
top of his keyboard, but he like to have his numeric keyboard keys back.
What can be wrong?

Paul Moortgat